Wind turbines are used to produce electrical energy using a renewable resource and without combusting a fossil fuel. Generally, a wind turbine converts kinetic energy from the wind into electrical power. A horizontal-axis wind turbine includes a tower, a nacelle located at the apex of the tower, and a rotor having a plurality of blades and supported in the nacelle by means of a shaft. The shaft couples the rotor either directly or indirectly with a generator, which is housed inside the nacelle. Consequently, as wind forces the blades to rotate, electrical energy is produced by the generator.
Wind turbines are subject to high aerodynamic loads applied by the wind to the wind turbine blades, including reduced lift forces caused by the separation of air flow around the blade from the blade surface at a boundary layer. As well understood in fluid dynamics, the thickness of a boundary layer tends to increase away from the leading edge of a wind turbine blade. The increased thickness of the boundary layer tends to promote turbulent flow within the boundary layer and reduce the maximum lift coefficient of the wind turbine blade. Consequently, vortex generators are positioned within the boundary layer to create vortices downstream of the vortex generators. The flow vortices force increased mixing of air from the boundary layer and air outside the boundary layer, thereby delaying the boundary layer separation or the rapid increase of thickness in the boundary layer. In this regard, the boundary layer remains closer to the surface of the blade over an increased portion of the wind turbine blade. Therefore, the vortex generators increase the maximum lift coefficient of a wind turbine blade by delaying separation.
Conventional vortex generators for wind turbine blades are generally applied to a blade after the blade has been manufactured because the vortex generators are small features difficult to successfully demold from a 160-foot long (50 meters) or longer blade mold. The vortex generators are typically plate-shaped members composed of a plastic or metal material and adhesively coupled to the outer surface of a wind turbine blade using double-sided tape or similar adhesive materials. The vortex generators must be accurately positioned and then manually adhered on the blade, typically in a piecemeal manner. This individualized process increases the time and cost for producing a wind turbine blade. Furthermore, the affixed vortex generators may be damaged in shipping or from repeated extreme weather conditions.
Thus, there remains a need for an improved molding apparatus and method for manufacturing the wind turbine blades and the vortex generators that address these and other shortcomings in conventional wind turbine manufacturing processes and conventional vortex generators.